By Norman Keitges, Novinium
Dayton Power and Light (DP&L) is a utility company serving 515,000 customers throughout Ohio’s Miami Valley. One of Dayton Power and Light’s most critical customers is the Dayton International Airport, which the Department of Homeland Security classifies as a vital asset to the nation’s security under the Critical Infrastructure Protection rogram.
DP&L is responsible for ensuring the reliability of the airport’s electrical supply and eliminating any potential electrical cable failures. After a main feeder cable supplying power to the airport terminal experienced a couple of events in 2014, DP&L needed a solution to ensure reliable power for this critical customer and needed it quickly.
(Editor’s note: a video on this project can be found on YouTube at this link)
Dayton International Airport:
Perhaps no other single spot on the globe has seen more aviation firsts than Dayton, Ohio. It all began when two brothers from Dayton, Orville and Wilbur Wright, began their search for the secrets of powered flight in 1896. Seven years later, on December 17, 1903, the Wright brothers successfully launched the world’s first man-carrying flying machine at Kitty Hawk, North Carolina.
On Dec. 17, 1936, 33 years to the day after the Wright brothers’ first flight, a dedication ceremony was held to officially open the Dayton Municipal Airport. The airport featured three 3,600-foot concrete runways and connecting taxiways. Soon after its opening, Trans Continental Airlines and Western Airways, later to be called TWA, began service with three daily flights.
Today, the Dayton International Airport covers more than 4,500 acres, and encompasses approximately 4.7 miles of runway. The airport is served by nine airlines. Some 70 flights arrive and depart daily from 17 active airline gates. In 2007, the Airport experienced passenger growth in excess of 8 percent for a total of 2,833,103 passengers served. The Dayton International Airport has a $1 billion economic impact on the regional economy, according to state of Ohio data.
After careful examination of the electrical power cable supplying the airport, DP&L determined that more than 40,000 feet of cable in two feeders needed to be replaced or rejuvenated and it was critical that it be done quickly. Ultimately, the utility determined the project needed to be completed in less than two months, leaving little time for planning and project completion.
Electrical cable rejuvenation is an alternative to cable replacement that restores feeder cable to its full dielectric strength for a fraction of the cost of cable replacement with minimal operational disruption. DP&L had completed a feeder cable rejuvenation project a few years earlier and given the short timeline for this project decided that rejuvenation was the best alternative in this case. The utility chose to rejuvenate both the 1,000 circular mils (MCM) and 500 MCM feeder cables supplying the airport. It chose Novinium to execute the cable rejuvenation.
In addition to the short timeline, the cable that needed to be treated was both buried cable as well as cable in a manhole and conduit system, which added another challenge-confined space. Security was also an issue. Because this was occurring at an airport, all on-site personnel working on the project were required to be escorted on and off the premises by airport security.
The Process of Cable Rejuvenation
Electric cable rejuvenation is the injection of a silicone fluid into the strands of aging medium-voltage power cables. The fluid migrates into the conductor shield and insulation, modifying the insulation’s chemistry and extending cable life. In this case, DP&L chose to inject the CableCure 732/733® fluid, using Novinium’s Sustained Pressure Rejuvenation (SPR) process to treat all 42,255 feet of cable. DP&L chose this option because it restored the cable to full dielectric strength within seven days in addition to the fact that the process comes with a 40-year warranty.
The process of cable rejuvenation begins with isolating, testing and grounding the cable. The use of a time domain reflectometer is employed to check every segment for splices, neutral corrosion and length. Splices are pinpointed by using a radio frequency locator and a measuring wheel. Once this is complete, a pit must be dug to expose and remove the old splice. Next, a radial press is used to install new injection adaptors and a splice connector.
The craftwork is verified with a template for each termination and the injection tools are positioned accordingly. The process begins by injecting each sub-segment at a moderate pressure. For example, a 300-foot (100 meters) segment typically takes 30 minutes or less to inject. Once the actual injection is complete, the equipment is removed and the process is completed by installing standard elbows at each end. The final steps are re-energizing of the cable, restoring of the work pit and moving on to the next segment of cable to be injected. This process takes a single visit with an average of four hours.
To deal with the challenges of this project, Novinium identified the requirements and construction needs in advance, forecasted the work schedule and contingency plans and ordered supplies from around the country to arrive on-site quickly. The crews executing the craftwork were critical to the plan. Five crew members worked six- to seven-hour shifts inside the airport property while two additional crews worked outside the airport.
The upfront planning was successful as the project was completed in approximately three-weeks-well under the required time line.
“I was very pleased with Novinium’s dedication to the project. They were able to mobilize several crews out here to make sure it got done under tight time constraints,” said Jeff Dahlinghaus, operations manager at DP&L.
In the end, 42,255 feet of electrical cable was rejuvenated at the Dayton International Airport. Careful analysis of the costs showed that the cable rejuvenation process cost less than one-third as much as the alternative of cable replacement, which saved Dayton Power & Light about $530,000.
Reliability was key to this project because the Dayton International Airport is part of the government’s critical infrastructure. Dayton Power and Light verified that the electrical cable rejuvenation met their criteria for reliability. The rejuvenated cable has been restored to as-new condition and is covered by a 40-year warranty.
Norman E. Keitges is technical services manager at Novinium. He has been an engineering and project manager for more than 30 years specializing in fluid mechanics, hydraulics, R&D and new product development. His projects include everything from submarine power cables connecting islands to mainland grids, wind power generation, motion control, wireless control systems and power transmission. Keitges was recently awarded a patent for enhancing injection of power cables (N-Terâ„- process). He is an IEEE senior member, an ICC-Power & Engineering Society presenter and holds a bachelor of science degree in mechanical engineering from Washington State University.